The present invention relates to a reconfigurable element for supporting and positioning parts, particularly, but not exclusively, parts measured on a measuring machine.
In the following description, specific reference is made purely by way of example to the latter application.
As an alternative to conventional dedicated supporting fixtures, and to reduce retooling costs for measuring different parts, reconfigurable fixtures have been devised, as illustrated, for example, in Italian Patent Application n. TO94A-000209 filed on Mar. 22, 1994, by the present Applicant.
Briefly, such fixtures comprise a number of reconfigurable column type supporting elements, each of which substantially comprises a base secured in a predetermined position on the reference table, and a rod adjustable in height along an axis perpendicular to the reference table. Both location of the base and the height adjustment of the rod are performed manually, but using as a geometric reference a reference fixture fitted to the machine and positioned automatically by the machine within the measuring volume. The supporting element also comprises a top end integral with the rod, and which is made to cooperate with the reference fixture before the rod is locked with respect to the base, and before the base is locked onto the reference table.
Supporting elements of the above type present the following drawback.
The rod is locked in relation to the base, and the base in relation to the reference table, with the end of the supporting element engaging the reference fixture; and, as fairly strong forces are involved at this stage, structural stress may be produced in the supporting element, e.g. due to imperfect alignment of the end of the supporting element (engaging the reference fixture) and the base (locked to the reference table). Consequently, when the reference fixture is released from the end of the supporting element, the stress in the supporting element is relieved elastically, with the result that the end of the supporting element (which is fitted, in use, with an element for supporting, clamping or locating the part) is set to other than the theoretical position, thus creating a purely random, uncontrollable source of error.